The present invention relates to an arrangement for an opening roller having a plurality of teeth sequentially arranged in several circumferentially extending rows. The faces of the teeth are sloped with a face angle of about 12.degree. to 30.degree. against the rotational direction, and connect in the region of the bottoms of the teeth with a curvature to the back of the respectively preceeding tooth.
The structural design of an opening roller has a substantial influence upon the quality of open-end spinning. The fiber material supplied in the form of a fiber band is opened by means of the opening roller arrangement to single fibers which are subsequently transported to the spinning surface. The particular arrangement of the opening roller serves, on the one hand, to open the fiber material as much as possible to single fibers whereby it is essential that damage to the fibers, especially shortening, is minimized. Additionally, the arrangement of the opening roller serves to separate any impurities present in the fiber material from the fibers and to spin off the same from the transport pass. Furthermore, the arrangement has to be designed in such a manner that the fibers are capable of loosening themselves in a predetermined way along the circumference of the opening roller, thereby enabling the preferred transport via a fiber channel to the spinning surface.
In practice, an arrangement consisting of needles has also been utilized instead of the primarily used arrangement of teeth. The teeth of a toothed roller are sequentially arranged in several rows extending in a spiral in the circumferential direction and the faces of the teeth connect with a curvature in the area of the tooth feet with a curvature to the tooth backs of the respectively preceeding tooth. The teeth of the known arrangement exhibit a straight extending tooth face and tooth back whereby the face, dependent upon the fiber material to be processed, exhibits a curve in the radial plane (the so-called face angle) of about 12.degree. to 30.degree.. Such teeth penetrate into the fiber material relatively gently at first contact. However, it has become apparent that these teeth, especially in the area of the bottoms of the teeth, are subject to substantial wear. The fibers to be combed out slide on the tooth surfaces in close proximity to the bottom of the teeth where most of the combing effort is executed. These arrangements are further subject to some extent to the problem that dirt particles having short fibers sticking to them may also slide into the area of the teeth bottoms and are not immediately spun off. The danger then exists that these dirt particles are removed later and reach the spinning surface downstream of the opening roller.
An object of the present invention is the provision of an arrangement of the above-mentioned kind for an opening roller in such a manner as to allow gentle penetration by teeth into the fiber material.
Another object of the present invention is the provision of an opening roller arrangement wherein the combing process is carried out over a greater range of the faces of the individual teeth.
A further object of the present invention is the provision of an opening roller wherein uneven wear of the individual teeth is avoided.
An even further object of the present invention is the provision of an opening roller arrangement wherein dirt particles attached to short fibers are spun off before they can be transported downstream to a spinning surface.
These and other objects are attained in the provision of an opening roller arrangement wherein the teeth surfaces are provided with a curvature in the direction of rotational movement of the roller while in operation in such a manner that the teeth surfaces exhibit a face angle between 12.degree. and 30.degree., in the region of the teeth tips and connect in the area of the bottoms of the teeth with a face angle of about +5.degree. to about -5.degree. to the curvature leading to the bottom of the preceeding tooth.
This arrangement makes a face angle possible which results in a gentle penetration into the fiber material. At the same time, it is avoided that the fibers passing along the tooth face will all end up in the area of the bottom of the tooth. The actual combing process of the fibers is consequently executed over a greater range, of the teeth so that the combing effect is improved. Additionally, by providing a distribution of the combing process over a greater range a high amount in wear at a particular position is avoided. This will result in an increase in wear time of the arrangement. Another favorable result is that dirt particles attached to shorter fibers are caught only for a short period so that they can be spun off. Another advantage is that all fibers are removed more easily out of the arrangement so that the separation of the fibers at the separating station is improved.
In a further development of the invention, it is provided that the curvature of the tooth surfaces between the area of the tips and the feet of the teeth exhibit the same bending radius. This improvement is advantageous for reasons of manufacture. It is advantageously provided that the bending radius of the curvature of the tooth surfaces are in the range between 2.5 mm and 4.5 mm and preferably about 3.5 mm. These dimensions result in an especially effective opening characteristic with the commonly used dimensions of the arrangement with opening rollers.
In another development of the invention, it is provided that the tooth surfaces include in the outer region of the tooth tips a straight extending section of the length of about 1 mm which approximately connects tangentially to the curvature. It is thereby attained that the face angle remains constant over a predetermined length in the region of the tip of the tooth which is an advantage for the first penetration of the arrangement into the fiber material to be combed out.
In still another development of the invention, it is provided that the tooth bottoms are extended beyond a straight connection between the curvatures and the teeth tips against the rotational direction. This has the advantage that without essentially strengthening the teeth in the area of the teeth tips, the teeth shoulders are enlarged extending in the circumferential direction, thereby accelerating the fibers from the teeth of the opening roller and obtaining a higher speed. The drawing effect of the fibers is thereby also improved. This acceleration to a higher speed is attained without increasing the rotational velocity of the opening roller which would lead to an increased damaging effect on the fibers.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.